Our organic grade A maple syrup, bought in bulk, has gone slightly fermented in the fridge. If I were still in college, this would be great, but I am a bit older. What do I do with this stuff? Can I assume it is fine in baked goods? How can I accelerate my usage of it?

can you describe the fermented syrup? How does it smell / taste / look?
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DavidDec 21 '10 at 5:56

just like regular maple syrup, but a little bit like wine. We keep it in an airtight bottle with one of those ceramic stoppers. When we open the bottle, there is some pressure released: it pops. So I believe there is some fermentation going on. This is in the fridge, so it cannot be going wild.
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shabbychefDec 23 '10 at 1:17

"airtight" bottles and gas production indicate anaerobic bacteria, which are not Good Eats. Of course, "airtight" may not actually exclude much oxygen, particularly if you open the bottle frequently.
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kdgregoryApr 12 '11 at 13:16

/@kdgregory: the point behind airtight storage of syrup makes sense when it is bottled: namely finished syrup is at 219 F at sea level, so the hot syrup helps to keep the bottle sterile. (w/ home bottling you're supposed to put the bottle on its side for a few minutes after sealing so that the top of the bottle gets heated up) After it's been opened, the bacteria can get a start, if the sugar content is low enough. If you buy in bulk (are you talking 1 gallon qtys?), I'd seriously consider rebottling in smaller canning jars: minimize the amount of syrup you have "open" at a time.
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sibbaldiopsisApr 12 '11 at 23:43

3 Answers
3

Yeah, syrup can ferment + convert sugar to alcohol. It has more of a tendency to do so if the sugar content is lower -- I tend to err on the side of overconcentrating my syrup.

You can try boiling it for a while to see if the alcohol boils off + if the flavor is OK then use it... but I'd boil down a bit more first, to make sure the sugar content is back up to standards. Either boil until the boiling point is 7 degrees F higher than the boiling point of water at your altitude, or boil until the syrup "aprons" (e.g. starts to drip in a sheet rather than discrete drops; a flat edge of a metal spatula works well), with the former being more accurate if you have a good thermometer.

If the flavor remains after boiling, then try using in recipes -- perhaps in brownies/blondies or with ice cream.

+1 for the idea to reboil. Based on what I learned while helping a friend with his annual boil, it sounds like the producer did not take the syrup to the correct gravity.
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kdgregoryApr 12 '11 at 13:18